1. Field of the Invention
The present invention relates to a non-stationary or mobile antenna, and particularly to a non-stationary antenna which is designed to permit: the setting of the antenna for a desired resonance condition in the course of manufacture; the setting of the antenna for a desired resonance condition to meet particular resonance requirements in different applications when in use and independence of antenna characteristics from the surrounding condition which may vary while the non-stationary antenna is being carried.
2. Description of the Prior Art
As is well known, non-stationary antennas have been widely used. For instance, a car radio is equipped with a non-stationary antenna, and a portable radio is equipped with a non-stationary antenna One example of such a non-stationary antenna is disclosed in Japanese Utility Model Publication 48-2029. It has a coil-and-capacitor resonance circuit connected to a central antenna conductor. In the course of manufacture the length of the central antenna conductor and the capacitance and inductance of the resonator circuit are fixedly adjusted according to prescriptions, thus providing a fixed characteristic impedance. The fixing of the characteristic impedance of an antenna, however, prevents wide application of the antenna. In an attempt to expand the range of application the antenna is designed to permit the trimming of selected resonant circuit elements to meet particular requirements. For this purpose the resonator circuit is designed to have a variable capacitor, thereby permitting adjustment of the characteristic impedance of the antenna to meet a particular frequency request in the course of manufacture.
No matter which type of resonator circuit may be used, coil-and-capacitor series connection or coil-and-capacitor parallel connection, the central antenna conductor cannot be separated by the resonator circuit, remaining in the form of a single continuous conductor line. Also, the conventional non-stationary antenna uses a single resonator circuit. In the conventional non-stationary antenna its central antenna conductor can be adjusted in length, but it cannot be bent.
Thus, the defects of the conventional non-stationary antenna are as follows:
1. While one is carrying a wireless equipped with an antenna or while a car equipped with an antenna is running, the characteristics of the antenna is apt to vary from place to pace. Particularly, natural elevation or depression of the earth's surface, electrically conductive ground condition of a particular place, buildings of different heights etc. will affect the reflection of the radiated electromagnetic wave from the ground to the antenna. Also, the strength of the magnetic field on the earth's surface on terrestrial magnetism somewhat varies from place to place, and accordingly the effect caused by the magnetic field on the earth's surface on the antenna will vary. These variables will cause an induction current to flow in the antenna, and the induction current will vary while the antenna is moving, causing the variation of the set resonant frequency, radiation impedance, voltage standing wave ratio, radiation angle and other characteristics of the antenna To assure that the antenna remains in stable condition, the antenna must be independent from such variable factors. However, it is difficult to keep the antenna free from such surrounding valiables because the central antenna conductor is connected directly to the resonator circuit, thereby permitting such variation to affect the antenna. PA1 2. Sometimes, the antenna is carried in the rain snow. Sometimes, the antenna is put in contact with a metal object or human body. There is an occasion in which one must hold the antenna in one's hand. In these occasions the resonant frequency, frequency band width, radiation impedance, voltage standing wave ratio, radiation angle, gain and other characteristics of the antenna will vary. Such variation although not large in quantity, cannot be avoided so far as the central antenna conductor is connected to the resonator circuit. PA1 3. The antenna uses a single parallel or series resonator circuit. The resonator circuit has variable element for the sake of trimming its resonating frequency in the course of manufacture, thereby permitting the antenna to fit to a particular use of application. The use of a single resonator circuit with a variable element, however, prevents selection and fine adjustment of the resonance frequency among a wide range of frequency or exact determination of resonance frequency required for a particular application. PA1 4. The antenna is longitudinally extensible, but it cannot be bent. Particularly it cannot be bent and held in bending condition. When one carries the antenna on one's back, and when he lies on his front, the antenna is accordingly laid, thereby lowering the antenna's receiving capability.